In the design of industrial floor scrubbing machines it is common to mount the scrub brushes and their drive motors in a housing called a scrub head. This scrub head is commonly attached in some articulated manner to the frame of the machine so that the brushes can be raised for transport and lowered to the floor for working, and when working will bear against the floor even though it may undulate somewhat. The scrub head is variously mounted in front of, underneath amidships, or behind the machine frame, and a suction pickup squeegee is universally used to pick up the soiled scrub water. The scrub head and the squeegee are commonly within the width of the machine frame, for they are vulnerable to being damaged by collision with fixed objects if they extend much wider than the frame. A scrub brush within a machine frame width cannot scrub closely along a wall, however, because of the surrounding machine structure. So a scrubbing side brush is often provided at a front corner of the machine, extending out forwardly and laterally beyond the machine frame, to scrub along walls. Side brushes, however, are quite vulnerable to being damaged by collisions with fixed objects, and their scrubbing pattern on the floor often does not match the pattern of the main brushes. In sharp turns a side brush, because of its forward location, may track outside of the pickup squeegee and consequently leave a trail of water on the floor which has otherwise been damp dried by the squeegee.